闪烁光对C57BL／6小鼠屈光和眼轴的影响初步观察

目的 探讨闪烁光诱导小鼠实验性近视模型的有效性和可行性.方法 实验研究.将28日龄的健康C57BL/6（B6）小鼠45只随机分为对照组、闪烁光照组、形觉剥夺组,每组15只.对照组饲养在模拟的正常光照环境中,光照时间为早8：00至晚8：00,光照度为250 lx;晚8：00至早8：00为暗室环境,光照度为0 lx.闪烁光照组使用白色LED灯闪烁光照明,时间为早8：00至晚8：00,闪烁光照频率为2 Hz,明暗周期为50%,峰值光照度为250 lx,谷值光照度约为1 lx;晚8：00至早8：00为暗室环境,光照度为0 lx;闪烁光照6周后撤去闪烁光,在与对照组同样环境中再饲养2周.形觉剥夺组使用半透明塑料眼罩遮盖右眼,饲养在与对照组相同的光照环境中.分别在实验前以及实验后2周、4周、6周、8周使用红外偏心验光仪和动物专用的A超测定仪来测量所有小鼠右眼的屈光度及眼轴,同时观察小鼠眼部和行为学变化.组间屈光度和眼轴比较采用单因素方差分析,闪烁光照组屈光度比较采用配对t检验,闪烁光照组与对照组比较采用独立样本t检验,眼轴与时间及屈光度的相关性采用回归分析.结果 闪烁光照6周后,小鼠的屈光度较对照组发生了显著的近视性改变[（-2.49±1.32）D vs（6.26±1.18）D,P＜0.01],眼轴也显著增长[（3.12±0.04）mm vs（3.08±0.02）mm,P＜0.01].闪烁光照组小鼠不同时间点眼轴与屈光度之间呈正相关（r2=0.677,P＜0.01）.实验6周末,形觉剥夺组小鼠发生的近视程度高于闪烁光照组[（-6.42±2.21）D vs（-2.49±1.32）D,P＜0.05],眼轴增长也更为显著[（3.27±0.04）mm vs（3.12±0.04）mm,P＜0.05],但是眼罩较易脱落,经常需补戴,并有晶状体混浊发生.结论 闪烁光刺激可以成功诱导出小鼠实验性轴性近视,但近视程度低于形觉剥夺诱导,是一种更为安全、方便的近视模型诱导方法.

Effects of flickering light on refraction and axial changes in the C57BL/6 mouse

Objective To investigate the effectiveness and feasibility of inducing myopia in mice with flickering light (FL) stimulation. Methods Experimental study. Forty-five C57BL/6 (B6)mice at age 28 days were randomly divided into 3 groups: control group, FL group and form deprivation (FD) group. Mice in the control group were raised under an illumination of 250 lx from 8 :00 am to 8:00 pm, and 0 lx from 8:00 pm to 8:00 am. For the FL group, the mice were raised under an illumination of a 50% duty cycle at 2 Hz for 6 weeks. During each flicker cycle, luminance varied between the maximum and minimum light levels of 250 lx and 1 lx from 8:00 am to 8:00 pm and 0 lx from 8:00 pm to 8 :00 am. Mter 6 weeks of FL, mice were raised under the same conditions as the control group for 2 weeks. Form deprivation was accomplished by covering the right eye of the mouse with a semitransparent hemispherical thin plastic shell for an eye diffuser.Mice in FD were raised under the same conditions as the control group. The refractive state and axial length (AL) of the right eye were measured with murine-specific eccentric infrared photorefraction and A-scan ultrasonography, respectively. The data were collected at pre-treatment and at the end of 2, 4, 6 and 8 weeks post-treatment. During the experiment, the eyes and action of all the mice were also observed. A one-way ANOVA was used to compare refraction and AL between groups. A paired t test was used to compare refraction and AL before and after flicker in FL group. An independent samples t test was used to compare refraction and AL between FL group and control group. Correlation between AL and time, refraction was analyzed with a Regression analysis. Results After 6 weeks of FL stimulation, refraction became more myopic compared to the control group [(-2.49+1.32)D versus (6.26±1.18)D, P＜0.01)], and their AL increased faster [(3.12±0.04)mm versus (3.08±0.02)mm], P＜0.01]. A positive correlation between refractive error and AL was found after treatment (r2=0.677, P＜0.01). The myopic shift decreased towards hyperopia after the removal of FL stimulation. After 6 weeks of FD, FD eyes were more myopic than FL eyes [(-6.42±2.21)D versus (-2.49±1.32)D, P＜0.05]. The AL of the FD eyes was longer than those of the FL eyes [(3.27±0.04)mm versus (3.12±0.04)mm, P＜0.05). However, some mice lost their eye diffusers, and in some mice lens opacities were found. Conclusion Myopia can be induced by FL stimulation in the B6 mouse. A myopic shift induced by FL is less than that by FD, but there are fewer side effects from FL, and FL is safer and easier to manipulate.